Skip to content

note.md

Latest commit

 

History

History
57 lines (43 loc) · 1.95 KB

note.md

File metadata and controls

57 lines (43 loc) · 1.95 KB

Notes

[SETUP] Before cloning the image, need to reset all machine identify files

Clean up machine-specific files

sudo virt-customize -a /path/to/your/image.img
--delete /etc/machine-id
--delete /var/lib/dbus/machine-id
--touch /etc/machine-id
--delete /etc/ssh/ssh_host_rsa_key
--delete /etc/ssh/ssh_host_rsa_key.pub
--delete /etc/ssh/ssh_host_ecdsa_key
--delete /etc/ssh/ssh_host_ecdsa_key.pub
--delete /etc/ssh/ssh_host_ed25519_key
--delete /etc/ssh/ssh_host_ed25519_key.pub

[SETUP] Adding permissions to libvirt images directory

Create a dedicated subdirectory with appropriate permissions

sudo mkdir /var/libvirt/images/yourusername sudo chown yourusername:yourusername /var/libvirt/images/yourusername

[RUN] Qemu create image

sudo qemu-img create -b /var/lib/libvirt/images/alexng/base/focal-server-cloudimg-amd64.img -f qcow2 -F qcow2 /var/lib/libvirt/images/alexng/7a4a5c55-000c-44d5-b41e-903b71bf32fe/focal-server-cloudimg-amd64.img

[CODE] Code rules

  • Calling to other services must use saga pattern to ensure that the system is resilient to failures and can recover gracefully. Eg: service A calls service B, if service B fails, service A should run the compensating transaction to revert the changes made by service A.

The difference between = NULL and IS NULL is fundamental in SQL: = NULL vs IS NULL = NULL

Always evaluates to UNKNOWN (which is treated as FALSE in WHERE clauses) This is because NULL represents "unknown value" in SQL Comparing anything to an unknown value results in unknown

IS NULL

Proper way to check for NULL values Returns TRUE if the value is NULL, FALSE if it's not NULL => This query works fine! -- name: GetAccount :one SELECT b., u. FROM "account"."base" b LEFT JOIN "account"."user" u ON b.id = u.id WHERE ( (b.type = sqlc.arg('type')) AND (b.id = sqlc.narg('id') OR b.username = sqlc.narg('username') OR u.email = sqlc.narg('email') OR u.phone = sqlc.narg('phone')) );